DIY





MAX Update No. 90: Why 'Real Old' Beats 'Old'


| 3/23/2012 3:48:11 PM



The secret to good mileage is streamlining and light weight. Okay, two secrets. Streamlining is essential at highway speeds, light weight is essential in city driving, and the two combined allow one to get satisfactory performance with a small engine. If you cut your car’s drag in half (via streamlining) and cut your car’s mass in half (via weight reduction) you can cut your horsepower in half without losing any performance. At present, MAX’s top speed is 90 mph, which is faster than I have any reason to drive, and that’s on 32 horsepower.

This is why my recent automotive designs look much like 50 year old road racing cars. Race cars have always focused on functionality, but after 1960, the function of race car bodies changed.

Before I leap into sports car racing history, I’d like to point out that streamlining hasn’t changed much in my lifetime.

090aLakestersHere are two “Lakester” class land speed record cars; both were record holders in their day. The rules require exposed wheels but the body shape is up to the builder. Note the visible similarity between these two cars; both have rounded fronts tapering to small sterns, though the upper car body was built in 1952 from a WWII fighter plane fuel tank, and the lower car body was built in 2004 from carbon fiber and polycarbonate. The shapes are slightly compromised by practical needs (the older car has a plexiglass bump on top so the driver can see out, the lower car has a scoop on top to let air in to the radiator) but they’re clearly built for the same purpose—going as fast as possible on a dry lakebed—and form follows function.

Compare those 50 years of lakesters with 10 years of road racers. You can’t tell by looking that a 1970 Le Mans car comes from the same sport as a 1960 Le Mans car—you can barely tell they come from the same planet.



Up to 1960, the limits of horsepower technology forced race car designers to focus on vehicle efficiency, in order to win races. The closest MAX look-alike is the Lola Mk1, a 75 horsepower two-seat sports racer with a great track record from 1958 to the early '60s, including a class win at the 1960 24 Hours of Le Mans.

Carlos Monteiro-Bonifacio
4/15/2012 8:49:36 PM

In South Africa 150 mph will get you locked up and you loose your license for one year and as this is a criminal offence you automatically get a criminal record. In real life 80 mph is more than enough and it is at this speed that I intend to get 33.33 kms per litre. At lower speeds 40 kms per litre could well be achieved, but I would like to keep up with the traffic flow.


Carlos Monteiro-Bonifacio
4/15/2012 8:33:01 PM

Everyone is a critic. John - your minimalistic Locost, heck 32hp is minimalistic but your fuel consumption is awesome. I particularly liked your Lotus 11 comment; Frank Costin was truly a great aerodynamicist and his work whilst not very well known, outstanding. like you I intend, in the near future, to produce a Max like vehicle. The car will be as a close a replica as possible of the original Marcos GT and like the original will be a wooden monocoque and the powerplant will a Citroen 1.4 turbo Hdi Diesel motor using a six speed box geared to give 60 k.p.h.per 1000rpm in top. I am still doing research and will build a 1/4 model first to refine the building process and do basic aerodynamic testing. My aim is to achieve 94 miles per Imperial gallon which equates to 33.33 kms per litre. The original C3 in which the motor was fitted manages 25 kms per litre = 70 miles per imperila gallon with little effort. With a mass goal slightly higher than yours at 1 210 lbs and a frontal area much smaller than the C3, a 33.3% improvement should be achievable. I have already scratch (plan) built a 3 wheeler, the Tri-Magnum, so this should be emminently doable.


JACK MCCORNACK
4/8/2012 9:13:19 PM

> Mileage is like horsepower, you can get what you are willing to pay for! True enough, Abbey, though as MAX demonstrates, you don't have to pay for it with money. I'm willing to pay with comfort and acceleration and a whole lot of design and construction work. But I think I've overdone the comfort sacrifice, and since there's still a little money in the budget, I'm going to invest in an enclosed cabin. If weatherproofing drops MAX's mileage to, say, 90 mpg, but lets me drive it in comfort when it's raining, I'll use MAX more and other cars less, which will improve my personal fuel consumption. Of course, I'll make the enclosure (roof, windows, different doors) removable -- it doesn't rain in Oregon -all- the time and MAX is such a treat on sunny days.




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